Lifecycle Carbon Footprint and Economic Feasibility of Net-Zero Buildings: A Multi-Dimensional BIM–Excel Framework for Sustainable Material Selection in Tropical Climates of Patna, India

Abstract

The building sector is a major contributor to global greenhouse gas emissions while rising focus on embodied carbon appears after net-zero buildings reach their energy needs. The research presents a framework that combines Building Information Modelling (BIM) with Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) and climate-responsive analysis to help choose materials for sustainable tropical ecosystem design. The framework uses BIM-based quantity extraction together with an Excel database that contains emission factors and cost parameters and climate performance indicators to support decision-making during the initial project stages. The framework proved effective through a residential case study which took place in Patna. The study shows that selecting the best materials can decrease embodied carbon between 30 and 35 percent which results in total emissions reduction from 400 to 420 kgCO₂e/m² down to 270 to 290 kgCO₂e/m². The study found that structural components made up almost 50 percent of all lifecycle emissions followed by wall systems as the second largest source. Sustainable construction materials increase first building expenses by 10 to 15 percent but lifecycle cost analysis shows total savings of 8 to 10 percent with a 5 to 8 year payback duration because operational energy expenses decrease. The climate performance index system enables architects to select materials which function best in hot-humid conditions, resulting in thermal efficiency improvements and cooling load reductions that reach 25 to 35 percent. The development of a multi-objective optimization model continues as it establishes a framework which designers and policymakers can use to assess three factors: carbon emissions and costs and climate performance. The proposed BIM–Excel framework offers a practical, scalable, and low-cost solution for sustainable building design, particularly in developing regions. The study advances net-zero building strategies while establishing policies for low-carbon construction in tropical climates through its environmental, economic, and climatic research dimensions.